X-Git-Url: https://git.ralfj.de/rust-101.git/blobdiff_plain/9f6c55ebcab2e1d3073e8bb6c8c910d0116efee4..ccf917e1f212cb8f8b07331ec60011f270621dd4:/workspace/src/part08.rs?ds=sidebyside diff --git a/workspace/src/part08.rs b/workspace/src/part08.rs index 2d3b5d8..0118906 100644 --- a/workspace/src/part08.rs +++ b/workspace/src/part08.rs @@ -7,15 +7,13 @@ use part05::BigInt; // So, let us write a function to "add with carry", and give it the appropriate type. Notice Rust's native support for pairs. fn overflowing_add(a: u64, b: u64, carry: bool) -> (u64, bool) { - let sum = u64::wrapping_add(a, b); + let sum = a.wrapping_add(b); // If an overflow happened, then the sum will be smaller than *both* summands. Without an overflow, of course, it will be // at least as large as both of them. So, let's just pick one and check. if sum >= a { // The addition did not overflow.
// **Exercise 08.1**: Write the code to handle adding the carry in this case. - let sum_total = u64::wrapping_add(sum, if carry { 1 } else { 0 }); /*@@*/ - let had_overflow = sum_total < sum; /*@@*/ - (sum_total, had_overflow) /*@@*/ + unimplemented!() } else { // Otherwise, the addition *did* overflow. It is impossible for the addition of the carry // to overflow again, as we are just adding 0 or 1. @@ -54,10 +52,7 @@ impl ops::Add for BigInt { unimplemented!() } // **Exercise 08.2**: Handle the final `carry`, and return the sum. - if carry { /*@@*/ - result_vec.push(1); /*@@*/ - } /*@@*/ - BigInt { data: result_vec } /*@@*/ + unimplemented!() } } @@ -81,7 +76,9 @@ impl<'a, 'b> ops::Add<&'a BigInt> for &'b BigInt { // Rust calls a bunch of definitions that are grouped together a *module*. You can put the tests in a submodule as follows. #[cfg(test)] mod tests { - #[test] + use part05::BigInt; + + /*#[test]*/ fn test_add() { let b1 = BigInt::new(1 << 32); let b2 = BigInt::from_vec(vec![0, 1]);